src/miner.cpp

   1 // Copyright (c) 2009-2010 Satoshi Nakamoto
   2 // Copyright (c) 2009-2016 The Bitcoin Core developers
   3 // Distributed under the MIT software license, see the accompanying
   4 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   5
   6 #include "miner.h"
   7
   8 #include "amount.h"
   9 #include "chain.h"
  10 #include "chainparams.h"
  11 #include "coins.h"
  12 #include "consensus/consensus.h"
  13 #include "consensus/merkle.h"
  14 #include "consensus/validation.h"
  15 #include "hash.h"
  16 #include "validation.h"
  17 #include "net.h"
  18 #include "policy/policy.h"
  19 #include "pow.h"
  20 #include "primitives/transaction.h"
  21 #include "script/standard.h"
  22 #include "timedata.h"
  23 #include "txmempool.h"
  24 #include "util.h"
  25 #include "utilmoneystr.h"
  26 #include "validationinterface.h"
  27
  28 #include <algorithm>
  29 #include <boost/thread.hpp>
  30 #include <boost/tuple/tuple.hpp>
  31 #include <queue>
  32 #include <utility>
  33
  34 //////////////////////////////////////////////////////////////////////////////
  35 //
  36 // BitcoinMiner
  37 //
  38
  39 //
  40 // Unconfirmed transactions in the memory pool often depend on other
  41 // transactions in the memory pool. When we select transactions from the
  42 // pool, we select by highest priority or fee rate, so we might consider
  43 // transactions that depend on transactions that aren't yet in the block.
  44
  45 uint64_t nLastBlockTx = 0;
  46 uint64_t nLastBlockSize = 0;
  47 uint64_t nLastBlockWeight = 0;
  48
  49 class ScoreCompare
  50 {
  51 public:
  52     ScoreCompare() {}
  53
  54     bool operator()(const CTxMemPool::txiter a, const CTxMemPool::txiter b)
  55     {
  56         return CompareTxMemPoolEntryByScore()(*b,*a); // Convert to less than
  57     }
  58 };
  59
  60 int64_t UpdateTime(CBlockHeader* pblock, const Consensus::Params& consensusParams, const CBlockIndex* pindexPrev)
  61 {
  62     int64_t nOldTime = pblock->nTime;
  63     int64_t nNewTime = std::max(pindexPrev->GetMedianTimePast()+1, GetAdjustedTime());
  64
  65     if (nOldTime < nNewTime)
  66         pblock->nTime = nNewTime;
  67
  68     // Updating time can change work required on testnet:
  69     if (consensusParams.fPowAllowMinDifficultyBlocks)
  70         pblock->nBits = GetNextWorkRequired(pindexPrev, pblock, consensusParams);
  71
  72     return nNewTime - nOldTime;
  73 }
  74
  75 BlockAssembler::BlockAssembler(const CChainParams& _chainparams)
  76     : chainparams(_chainparams)
  77 {
  78     // Block resource limits
  79     // If neither -blockmaxsize or -blockmaxweight is given, limit to DEFAULT_BLOCK_MAX_*
  80     // If only one is given, only restrict the specified resource.
  81     // If both are given, restrict both.
  82     nBlockMaxWeight = DEFAULT_BLOCK_MAX_WEIGHT;
  83     nBlockMaxSize = DEFAULT_BLOCK_MAX_SIZE;
  84     bool fWeightSet = false;
  85     if (IsArgSet("-blockmaxweight")) {
  86         nBlockMaxWeight = GetArg("-blockmaxweight", DEFAULT_BLOCK_MAX_WEIGHT);
  87         nBlockMaxSize = MAX_BLOCK_SERIALIZED_SIZE;
  88         fWeightSet = true;
  89     }
  90     if (IsArgSet("-blockmaxsize")) {
  91         nBlockMaxSize = GetArg("-blockmaxsize", DEFAULT_BLOCK_MAX_SIZE);
  92         if (!fWeightSet) {
  93             nBlockMaxWeight = nBlockMaxSize * WITNESS_SCALE_FACTOR;
  94         }
  95     }
  96     if (IsArgSet("-blockmintxfee")) {
  97         CAmount n = 0;
  98         ParseMoney(GetArg("-blockmintxfee", ""), n);
  99         blockMinFeeRate = CFeeRate(n);
 100     } else {
 101         blockMinFeeRate = CFeeRate(DEFAULT_BLOCK_MIN_TX_FEE);
 102     }
 103
 104     // Limit weight to between 4K and MAX_BLOCK_WEIGHT-4K for sanity:
 105     nBlockMaxWeight = std::max((unsigned int)4000, std::min((unsigned int)(MAX_BLOCK_WEIGHT-4000), nBlockMaxWeight));
 106     // Limit size to between 1K and MAX_BLOCK_SERIALIZED_SIZE-1K for sanity:
 107     nBlockMaxSize = std::max((unsigned int)1000, std::min((unsigned int)(MAX_BLOCK_SERIALIZED_SIZE-1000), nBlockMaxSize));
 108     // Whether we need to account for byte usage (in addition to weight usage)
 109     fNeedSizeAccounting = (nBlockMaxSize < MAX_BLOCK_SERIALIZED_SIZE-1000);
 110 }
 111
 112 void BlockAssembler::resetBlock()
 113 {
 114     inBlock.clear();
 115
 116     // Reserve space for coinbase tx
 117     nBlockSize = 1000;
 118     nBlockWeight = 4000;
 119     nBlockSigOpsCost = 400;
 120     fIncludeWitness = false;
 121
 122     // These counters do not include coinbase tx
 123     nBlockTx = 0;
 124     nFees = 0;
 125
 126     lastFewTxs = 0;
 127     blockFinished = false;
 128 }
 129
 130 std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock(const CScript& scriptPubKeyIn)
 131 {
 132     resetBlock();
 133
 134     pblocktemplate.reset(new CBlockTemplate());
 135
 136     if(!pblocktemplate.get())
 137         return nullptr;
 138     pblock = &pblocktemplate->block; // pointer for convenience
 139
 140     // Add dummy coinbase tx as first transaction
 141     pblock->vtx.emplace_back();
 142     pblocktemplate->vTxFees.push_back(-1); // updated at end
 143     pblocktemplate->vTxSigOpsCost.push_back(-1); // updated at end
 144
 145     LOCK2(cs_main, mempool.cs);
 146     CBlockIndex* pindexPrev = chainActive.Tip();
 147     nHeight = pindexPrev->nHeight + 1;
 148
 149     pblock->nVersion = ComputeBlockVersion(pindexPrev, chainparams.GetConsensus());
 150     // -regtest only: allow overriding block.nVersion with
 151     // -blockversion=N to test forking scenarios
 152     if (chainparams.MineBlocksOnDemand())
 153         pblock->nVersion = GetArg("-blockversion", pblock->nVersion);
 154
 155     pblock->nTime = GetAdjustedTime();
 156     const int64_t nMedianTimePast = pindexPrev->GetMedianTimePast();
 157
 158     nLockTimeCutoff = (STANDARD_LOCKTIME_VERIFY_FLAGS & LOCKTIME_MEDIAN_TIME_PAST)
 159                        ? nMedianTimePast
 160                        : pblock->GetBlockTime();
 161
 162     // Decide whether to include witness transactions
 163     // This is only needed in case the witness softfork activation is reverted
 164     // (which would require a very deep reorganization) or when
 165     // -promiscuousmempoolflags is used.
 166     // TODO: replace this with a call to main to assess validity of a mempool
 167     // transaction (which in most cases can be a no-op).
 168     fIncludeWitness = IsWitnessEnabled(pindexPrev, chainparams.GetConsensus());
 169
 170     addPriorityTxs();
 171     addPackageTxs();
 172
 173     nLastBlockTx = nBlockTx;
 174     nLastBlockSize = nBlockSize;
 175     nLastBlockWeight = nBlockWeight;
 176
 177     // Create coinbase transaction.
 178     CMutableTransaction coinbaseTx;
 179     coinbaseTx.vin.resize(1);
 180     coinbaseTx.vin[0].prevout.SetNull();
 181     coinbaseTx.vout.resize(1);
 182     coinbaseTx.vout[0].scriptPubKey = scriptPubKeyIn;
 183     coinbaseTx.vout[0].nValue = nFees + GetBlockSubsidy(nHeight, chainparams.GetConsensus());
 184     coinbaseTx.vin[0].scriptSig = CScript() << nHeight << OP_0;
 185     pblock->vtx[0] = MakeTransactionRef(std::move(coinbaseTx));
 186     pblocktemplate->vchCoinbaseCommitment = GenerateCoinbaseCommitment(*pblock, pindexPrev, chainparams.GetConsensus());
 187     pblocktemplate->vTxFees[0] = -nFees;
 188
 189     uint64_t nSerializeSize = GetSerializeSize(*pblock, SER_NETWORK, PROTOCOL_VERSION);
 190     LogPrintf("CreateNewBlock(): total size: %u block weight: %u txs: %u fees: %ld sigops %d\n", nSerializeSize, GetBlockWeight(*pblock), nBlockTx, nFees, nBlockSigOpsCost);
 191
 192     // Fill in header
 193     pblock->hashPrevBlock  = pindexPrev->GetBlockHash();
 194     UpdateTime(pblock, chainparams.GetConsensus(), pindexPrev);
 195     pblock->nBits          = GetNextWorkRequired(pindexPrev, pblock, chainparams.GetConsensus());
 196     pblock->nNonce         = 0;
 197     pblocktemplate->vTxSigOpsCost[0] = WITNESS_SCALE_FACTOR * GetLegacySigOpCount(*pblock->vtx[0]);
 198
 199     CValidationState state;
 200     if (!TestBlockValidity(state, chainparams, *pblock, pindexPrev, false, false)) {
 201         throw std::runtime_error(strprintf("%s: TestBlockValidity failed: %s", __func__, FormatStateMessage(state)));
 202     }
 203
 204     return std::move(pblocktemplate);
 205 }
 206
 207 bool BlockAssembler::isStillDependent(CTxMemPool::txiter iter)
 208 {
 209     BOOST_FOREACH(CTxMemPool::txiter parent, mempool.GetMemPoolParents(iter))
 210     {
 211         if (!inBlock.count(parent)) {
 212             return true;
 213         }
 214     }
 215     return false;
 216 }
 217
 218 void BlockAssembler::onlyUnconfirmed(CTxMemPool::setEntries& testSet)
 219 {
 220     for (CTxMemPool::setEntries::iterator iit = testSet.begin(); iit != testSet.end(); ) {
 221         // Only test txs not already in the block
 222         if (inBlock.count(*iit)) {
 223             testSet.erase(iit++);
 224         }
 225         else {
 226             iit++;
 227         }
 228     }
 229 }
 230
 231 bool BlockAssembler::TestPackage(uint64_t packageSize, int64_t packageSigOpsCost)
 232 {
 233     // TODO: switch to weight-based accounting for packages instead of vsize-based accounting.
 234     if (nBlockWeight + WITNESS_SCALE_FACTOR * packageSize >= nBlockMaxWeight)
 235         return false;
 236     if (nBlockSigOpsCost + packageSigOpsCost >= MAX_BLOCK_SIGOPS_COST)
 237         return false;
 238     return true;
 239 }
 240
 241 // Perform transaction-level checks before adding to block:
 242 // - transaction finality (locktime)
 243 // - premature witness (in case segwit transactions are added to mempool before
 244 //   segwit activation)
 245 // - serialized size (in case -blockmaxsize is in use)
 246 bool BlockAssembler::TestPackageTransactions(const CTxMemPool::setEntries& package)
 247 {
 248     uint64_t nPotentialBlockSize = nBlockSize; // only used with fNeedSizeAccounting
 249     BOOST_FOREACH (const CTxMemPool::txiter it, package) {
 250         if (!IsFinalTx(it->GetTx(), nHeight, nLockTimeCutoff))
 251             return false;
 252         if (!fIncludeWitness && it->GetTx().HasWitness())
 253             return false;
 254         if (fNeedSizeAccounting) {
 255             uint64_t nTxSize = ::GetSerializeSize(it->GetTx(), SER_NETWORK, PROTOCOL_VERSION);
 256             if (nPotentialBlockSize + nTxSize >= nBlockMaxSize) {
 257                 return false;
 258             }
 259             nPotentialBlockSize += nTxSize;
 260         }
 261     }
 262     return true;
 263 }
 264
 265 bool BlockAssembler::TestForBlock(CTxMemPool::txiter iter)
 266 {
 267     if (nBlockWeight + iter->GetTxWeight() >= nBlockMaxWeight) {
 268         // If the block is so close to full that no more txs will fit
 269         // or if we've tried more than 50 times to fill remaining space
 270         // then flag that the block is finished
 271         if (nBlockWeight >  nBlockMaxWeight - 400 || lastFewTxs > 50) {
 272              blockFinished = true;
 273              return false;
 274         }
 275         // Once we're within 4000 weight of a full block, only look at 50 more txs
 276         // to try to fill the remaining space.
 277         if (nBlockWeight > nBlockMaxWeight - 4000) {
 278             lastFewTxs++;
 279         }
 280         return false;
 281     }
 282
 283     if (fNeedSizeAccounting) {
 284         if (nBlockSize + ::GetSerializeSize(iter->GetTx(), SER_NETWORK, PROTOCOL_VERSION) >= nBlockMaxSize) {
 285             if (nBlockSize >  nBlockMaxSize - 100 || lastFewTxs > 50) {
 286                  blockFinished = true;
 287                  return false;
 288             }
 289             if (nBlockSize > nBlockMaxSize - 1000) {
 290                 lastFewTxs++;
 291             }
 292             return false;
 293         }
 294     }
 295
 296     if (nBlockSigOpsCost + iter->GetSigOpCost() >= MAX_BLOCK_SIGOPS_COST) {
 297         // If the block has room for no more sig ops then
 298         // flag that the block is finished
 299         if (nBlockSigOpsCost > MAX_BLOCK_SIGOPS_COST - 8) {
 300             blockFinished = true;
 301             return false;
 302         }
 303         // Otherwise attempt to find another tx with fewer sigops
 304         // to put in the block.
 305         return false;
 306     }
 307
 308     // Must check that lock times are still valid
 309     // This can be removed once MTP is always enforced
 310     // as long as reorgs keep the mempool consistent.
 311     if (!IsFinalTx(iter->GetTx(), nHeight, nLockTimeCutoff))
 312         return false;
 313
 314     return true;
 315 }
 316
 317 void BlockAssembler::AddToBlock(CTxMemPool::txiter iter)
 318 {
 319     pblock->vtx.emplace_back(iter->GetSharedTx());
 320     pblocktemplate->vTxFees.push_back(iter->GetFee());
 321     pblocktemplate->vTxSigOpsCost.push_back(iter->GetSigOpCost());
 322     if (fNeedSizeAccounting) {
 323         nBlockSize += ::GetSerializeSize(iter->GetTx(), SER_NETWORK, PROTOCOL_VERSION);
 324     }
 325     nBlockWeight += iter->GetTxWeight();
 326     ++nBlockTx;
 327     nBlockSigOpsCost += iter->GetSigOpCost();
 328     nFees += iter->GetFee();
 329     inBlock.insert(iter);
 330
 331     bool fPrintPriority = GetBoolArg("-printpriority", DEFAULT_PRINTPRIORITY);
 332     if (fPrintPriority) {
 333         double dPriority = iter->GetPriority(nHeight);
 334         CAmount dummy;
 335         mempool.ApplyDeltas(iter->GetTx().GetHash(), dPriority, dummy);
 336         LogPrintf("priority %.1f fee %s txid %s\n",
 337                   dPriority,
 338                   CFeeRate(iter->GetModifiedFee(), iter->GetTxSize()).ToString(),
 339                   iter->GetTx().GetHash().ToString());
 340     }
 341 }
 342
 343 void BlockAssembler::UpdatePackagesForAdded(const CTxMemPool::setEntries& alreadyAdded,
 344         indexed_modified_transaction_set &mapModifiedTx)
 345 {
 346     BOOST_FOREACH(const CTxMemPool::txiter it, alreadyAdded) {
 347         CTxMemPool::setEntries descendants;
 348         mempool.CalculateDescendants(it, descendants);
 349         // Insert all descendants (not yet in block) into the modified set
 350         BOOST_FOREACH(CTxMemPool::txiter desc, descendants) {
 351             if (alreadyAdded.count(desc))
 352                 continue;
 353             modtxiter mit = mapModifiedTx.find(desc);
 354             if (mit == mapModifiedTx.end()) {
 355                 CTxMemPoolModifiedEntry modEntry(desc);
 356                 modEntry.nSizeWithAncestors -= it->GetTxSize();
 357                 modEntry.nModFeesWithAncestors -= it->GetModifiedFee();
 358                 modEntry.nSigOpCostWithAncestors -= it->GetSigOpCost();
 359                 mapModifiedTx.insert(modEntry);
 360             } else {
 361                 mapModifiedTx.modify(mit, update_for_parent_inclusion(it));
 362             }
 363         }
 364     }
 365 }
 366
 367 // Skip entries in mapTx that are already in a block or are present
 368 // in mapModifiedTx (which implies that the mapTx ancestor state is
 369 // stale due to ancestor inclusion in the block)
 370 // Also skip transactions that we've already failed to add. This can happen if
 371 // we consider a transaction in mapModifiedTx and it fails: we can then
 372 // potentially consider it again while walking mapTx.  It's currently
 373 // guaranteed to fail again, but as a belt-and-suspenders check we put it in
 374 // failedTx and avoid re-evaluation, since the re-evaluation would be using
 375 // cached size/sigops/fee values that are not actually correct.
 376 bool BlockAssembler::SkipMapTxEntry(CTxMemPool::txiter it, indexed_modified_transaction_set &mapModifiedTx, CTxMemPool::setEntries &failedTx)
 377 {
 378     assert (it != mempool.mapTx.end());
 379     if (mapModifiedTx.count(it) || inBlock.count(it) || failedTx.count(it))
 380         return true;
 381     return false;
 382 }
 383
 384 void BlockAssembler::SortForBlock(const CTxMemPool::setEntries& package, CTxMemPool::txiter entry, std::vector<CTxMemPool::txiter>& sortedEntries)
 385 {
 386     // Sort package by ancestor count
 387     // If a transaction A depends on transaction B, then A's ancestor count
 388     // must be greater than B's.  So this is sufficient to validly order the
 389     // transactions for block inclusion.
 390     sortedEntries.clear();
 391     sortedEntries.insert(sortedEntries.begin(), package.begin(), package.end());
 392     std::sort(sortedEntries.begin(), sortedEntries.end(), CompareTxIterByAncestorCount());
 393 }
 394
 395 // This transaction selection algorithm orders the mempool based
 396 // on feerate of a transaction including all unconfirmed ancestors.
 397 // Since we don't remove transactions from the mempool as we select them
 398 // for block inclusion, we need an alternate method of updating the feerate
 399 // of a transaction with its not-yet-selected ancestors as we go.
 400 // This is accomplished by walking the in-mempool descendants of selected
 401 // transactions and storing a temporary modified state in mapModifiedTxs.
 402 // Each time through the loop, we compare the best transaction in
 403 // mapModifiedTxs with the next transaction in the mempool to decide what
 404 // transaction package to work on next.
 405 void BlockAssembler::addPackageTxs()
 406 {
 407     // mapModifiedTx will store sorted packages after they are modified
 408     // because some of their txs are already in the block
 409     indexed_modified_transaction_set mapModifiedTx;
 410     // Keep track of entries that failed inclusion, to avoid duplicate work
 411     CTxMemPool::setEntries failedTx;
 412
 413     // Start by adding all descendants of previously added txs to mapModifiedTx
 414     // and modifying them for their already included ancestors
 415     UpdatePackagesForAdded(inBlock, mapModifiedTx);
 416
 417     CTxMemPool::indexed_transaction_set::index<ancestor_score>::type::iterator mi = mempool.mapTx.get<ancestor_score>().begin();
 418     CTxMemPool::txiter iter;
 419     while (mi != mempool.mapTx.get<ancestor_score>().end() || !mapModifiedTx.empty())
 420     {
 421         // First try to find a new transaction in mapTx to evaluate.
 422         if (mi != mempool.mapTx.get<ancestor_score>().end() &&
 423                 SkipMapTxEntry(mempool.mapTx.project<0>(mi), mapModifiedTx, failedTx)) {
 424             ++mi;
 425             continue;
 426         }
 427
 428         // Now that mi is not stale, determine which transaction to evaluate:
 429         // the next entry from mapTx, or the best from mapModifiedTx?
 430         bool fUsingModified = false;
 431
 432         modtxscoreiter modit = mapModifiedTx.get<ancestor_score>().begin();
 433         if (mi == mempool.mapTx.get<ancestor_score>().end()) {
 434             // We're out of entries in mapTx; use the entry from mapModifiedTx
 435             iter = modit->iter;
 436             fUsingModified = true;
 437         } else {
 438             // Try to compare the mapTx entry to the mapModifiedTx entry
 439             iter = mempool.mapTx.project<0>(mi);
 440             if (modit != mapModifiedTx.get<ancestor_score>().end() &&
 441                     CompareModifiedEntry()(*modit, CTxMemPoolModifiedEntry(iter))) {
 442                 // The best entry in mapModifiedTx has higher score
 443                 // than the one from mapTx.
 444                 // Switch which transaction (package) to consider
 445                 iter = modit->iter;
 446                 fUsingModified = true;
 447             } else {
 448                 // Either no entry in mapModifiedTx, or it's worse than mapTx.
 449                 // Increment mi for the next loop iteration.
 450                 ++mi;
 451             }
 452         }
 453
 454         // We skip mapTx entries that are inBlock, and mapModifiedTx shouldn't
 455         // contain anything that is inBlock.
 456         assert(!inBlock.count(iter));
 457
 458         uint64_t packageSize = iter->GetSizeWithAncestors();
 459         CAmount packageFees = iter->GetModFeesWithAncestors();
 460         int64_t packageSigOpsCost = iter->GetSigOpCostWithAncestors();
 461         if (fUsingModified) {
 462             packageSize = modit->nSizeWithAncestors;
 463             packageFees = modit->nModFeesWithAncestors;
 464             packageSigOpsCost = modit->nSigOpCostWithAncestors;
 465         }
 466
 467         if (packageFees < blockMinFeeRate.GetFee(packageSize)) {
 468             // Everything else we might consider has a lower fee rate
 469             return;
 470         }
 471
 472         if (!TestPackage(packageSize, packageSigOpsCost)) {
 473             if (fUsingModified) {
 474                 // Since we always look at the best entry in mapModifiedTx,
 475                 // we must erase failed entries so that we can consider the
 476                 // next best entry on the next loop iteration
 477                 mapModifiedTx.get<ancestor_score>().erase(modit);
 478                 failedTx.insert(iter);
 479             }
 480             continue;
 481         }
 482
 483         CTxMemPool::setEntries ancestors;
 484         uint64_t nNoLimit = std::numeric_limits<uint64_t>::max();
 485         std::string dummy;
 486         mempool.CalculateMemPoolAncestors(*iter, ancestors, nNoLimit, nNoLimit, nNoLimit, nNoLimit, dummy, false);
 487
 488         onlyUnconfirmed(ancestors);
 489         ancestors.insert(iter);
 490
 491         // Test if all tx's are Final
 492         if (!TestPackageTransactions(ancestors)) {
 493             if (fUsingModified) {
 494                 mapModifiedTx.get<ancestor_score>().erase(modit);
 495                 failedTx.insert(iter);
 496             }
 497             continue;
 498         }
 499
 500         // Package can be added. Sort the entries in a valid order.
 501         std::vector<CTxMemPool::txiter> sortedEntries;
 502         SortForBlock(ancestors, iter, sortedEntries);
 503
 504         for (size_t i=0; i<sortedEntries.size(); ++i) {
 505             AddToBlock(sortedEntries[i]);
 506             // Erase from the modified set, if present
 507             mapModifiedTx.erase(sortedEntries[i]);
 508         }
 509
 510         // Update transactions that depend on each of these
 511         UpdatePackagesForAdded(ancestors, mapModifiedTx);
 512     }
 513 }
 514
 515 void BlockAssembler::addPriorityTxs()
 516 {
 517     // How much of the block should be dedicated to high-priority transactions,
 518     // included regardless of the fees they pay
 519     unsigned int nBlockPrioritySize = GetArg("-blockprioritysize", DEFAULT_BLOCK_PRIORITY_SIZE);
 520     nBlockPrioritySize = std::min(nBlockMaxSize, nBlockPrioritySize);
 521
 522     if (nBlockPrioritySize == 0) {
 523         return;
 524     }
 525
 526     bool fSizeAccounting = fNeedSizeAccounting;
 527     fNeedSizeAccounting = true;
 528
 529     // This vector will be sorted into a priority queue:
 530     std::vector<TxCoinAgePriority> vecPriority;
 531     TxCoinAgePriorityCompare pricomparer;
 532     std::map<CTxMemPool::txiter, double, CTxMemPool::CompareIteratorByHash> waitPriMap;
 533     typedef std::map<CTxMemPool::txiter, double, CTxMemPool::CompareIteratorByHash>::iterator waitPriIter;
 534     double actualPriority = -1;
 535
 536     vecPriority.reserve(mempool.mapTx.size());
 537     for (CTxMemPool::indexed_transaction_set::iterator mi = mempool.mapTx.begin();
 538          mi != mempool.mapTx.end(); ++mi)
 539     {
 540         double dPriority = mi->GetPriority(nHeight);
 541         CAmount dummy;
 542         mempool.ApplyDeltas(mi->GetTx().GetHash(), dPriority, dummy);
 543         vecPriority.push_back(TxCoinAgePriority(dPriority, mi));
 544     }
 545     std::make_heap(vecPriority.begin(), vecPriority.end(), pricomparer);
 546
 547     CTxMemPool::txiter iter;
 548     while (!vecPriority.empty() && !blockFinished) { // add a tx from priority queue to fill the blockprioritysize
 549         iter = vecPriority.front().second;
 550         actualPriority = vecPriority.front().first;
 551         std::pop_heap(vecPriority.begin(), vecPriority.end(), pricomparer);
 552         vecPriority.pop_back();
 553
 554         // If tx already in block, skip
 555         if (inBlock.count(iter)) {
 556             assert(false); // shouldn't happen for priority txs
 557             continue;
 558         }
 559
 560         // cannot accept witness transactions into a non-witness block
 561         if (!fIncludeWitness && iter->GetTx().HasWitness())
 562             continue;
 563
 564         // If tx is dependent on other mempool txs which haven't yet been included
 565         // then put it in the waitSet
 566         if (isStillDependent(iter)) {
 567             waitPriMap.insert(std::make_pair(iter, actualPriority));
 568             continue;
 569         }
 570
 571         // If this tx fits in the block add it, otherwise keep looping
 572         if (TestForBlock(iter)) {
 573             AddToBlock(iter);
 574
 575             // If now that this txs is added we've surpassed our desired priority size
 576             // or have dropped below the AllowFreeThreshold, then we're done adding priority txs
 577             if (nBlockSize >= nBlockPrioritySize || !AllowFree(actualPriority)) {
 578                 break;
 579             }
 580
 581             // This tx was successfully added, so
 582             // add transactions that depend on this one to the priority queue to try again
 583             BOOST_FOREACH(CTxMemPool::txiter child, mempool.GetMemPoolChildren(iter))
 584             {
 585                 waitPriIter wpiter = waitPriMap.find(child);
 586                 if (wpiter != waitPriMap.end()) {
 587                     vecPriority.push_back(TxCoinAgePriority(wpiter->second,child));
 588                     std::push_heap(vecPriority.begin(), vecPriority.end(), pricomparer);
 589                     waitPriMap.erase(wpiter);
 590                 }
 591             }
 592         }
 593     }
 594     fNeedSizeAccounting = fSizeAccounting;
 595 }
 596
 597 void IncrementExtraNonce(CBlock* pblock, const CBlockIndex* pindexPrev, unsigned int& nExtraNonce)
 598 {
 599     // Update nExtraNonce
 600     static uint256 hashPrevBlock;
 601     if (hashPrevBlock != pblock->hashPrevBlock)
 602     {
 603         nExtraNonce = 0;
 604         hashPrevBlock = pblock->hashPrevBlock;
 605     }
 606     ++nExtraNonce;
 607     unsigned int nHeight = pindexPrev->nHeight+1; // Height first in coinbase required for block.version=2
 608     CMutableTransaction txCoinbase(*pblock->vtx[0]);
 609     txCoinbase.vin[0].scriptSig = (CScript() << nHeight << CScriptNum(nExtraNonce)) + COINBASE_FLAGS;
 610     assert(txCoinbase.vin[0].scriptSig.size() <= 100);
 611
 612     pblock->vtx[0] = MakeTransactionRef(std::move(txCoinbase));
 613     pblock->hashMerkleRoot = BlockMerkleRoot(*pblock);
 614 }